|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v2 4/8] xen/ppc: Implement bitops.h
On 23.08.2023 22:07, Shawn Anastasio wrote:
> Implement bitops.h, based on Linux's implementation as of commit
> 5321d1b1afb9a17302c6cec79f0cbf823eb0d3fc. Though it is based off of
> Linux's implementation, this code diverges significantly in a number of
> ways:
> - Bitmap entries changed to 32-bit words to match X86 and Arm on Xen
> - PPC32-specific code paths dropped
> - Formatting completely re-done to more closely line up with Xen.
> Including 4 space indentation.
With this goal, ...
> --- a/xen/arch/ppc/include/asm/bitops.h
> +++ b/xen/arch/ppc/include/asm/bitops.h
> @@ -1,9 +1,335 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Adapted from Linux's arch/powerpc/include/asm/bitops.h.
> + *
> + * Merged version by David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>.
> + * Based on ppc64 versions by: Dave Engebretsen, Todd Inglett, Don
> + * Reed, Pat McCarthy, Peter Bergner, Anton Blanchard. They
> + * originally took it from the ppc32 code.
> + */
> #ifndef _ASM_PPC_BITOPS_H
> #define _ASM_PPC_BITOPS_H
>
> +#include <asm/memory.h>
> +
> +#define __set_bit(n,p) set_bit(n,p)
> +#define __clear_bit(n,p) clear_bit(n,p)
... you want to add blanks after the commas as well. (You might also
simply omit parameters altogether.)
> +#define BITOP_BITS_PER_WORD 32
> +#define BITOP_MASK(nr) (1UL << ((nr) % BITOP_BITS_PER_WORD))
> +#define BITOP_WORD(nr) ((nr) / BITOP_BITS_PER_WORD)
> +#define BITS_PER_BYTE 8
> +
> /* PPC bit number conversion */
> -#define PPC_BITLSHIFT(be) (BITS_PER_LONG - 1 - (be))
> -#define PPC_BIT(bit) (1UL << PPC_BITLSHIFT(bit))
> -#define PPC_BITMASK(bs, be) ((PPC_BIT(bs) - PPC_BIT(be)) | PPC_BIT(bs))
> +#define PPC_BITLSHIFT(be) (BITS_PER_LONG - 1 - (be))
> +#define PPC_BIT(bit) (1UL << PPC_BITLSHIFT(bit))
> +#define PPC_BITMASK(bs, be) ((PPC_BIT(bs) - PPC_BIT(be)) | PPC_BIT(bs))
> +
> +/* Macro for generating the ***_bits() functions */
> +#define DEFINE_BITOP(fn, op, prefix)
> \
> +static inline void fn(unsigned long mask,
> \
> + volatile unsigned int *_p)
> \
Nit: Style. Either
static inline void fn(unsigned long mask, \
volatile unsigned int *_p) \
or
static inline void fn(unsigned long mask, \
volatile unsigned int *_p) \
. Also there's again an underscore-prefixed identifier here.
> +{
> \
> + unsigned long old;
> \
> + unsigned int *p = (unsigned int *)_p;
> \
> + asm volatile (
> \
> + prefix
> \
> +"1: lwarx %0,0,%3,0\n"
> \
> + #op "%I2 %0,%0,%2\n"
> \
> + "stwcx. %0,0,%3\n"
> \
> + "bne- 1b\n"
> \
> + : "=&r" (old), "+m" (*p)
> \
> + : "rK" (mask), "r" (p)
> \
> + : "cc", "memory");
> \
The asm() body wants indenting by another four blanks (more instances below).
> +}
> +
> +DEFINE_BITOP(set_bits, or, "")
> +DEFINE_BITOP(change_bits, xor, "")
> +
> +#define DEFINE_CLROP(fn, prefix)
> \
> +static inline void fn(unsigned long mask, volatile unsigned int *_p)
> \
> +{
> \
> + unsigned long old;
> \
> + unsigned int *p = (unsigned int *)_p;
> \
> + asm volatile (
> \
> + prefix
> \
> +"1: lwarx %0,0,%3,0\n"
> \
> + "andc %0,%0,%2\n"
> \
> + "stwcx. %0,0,%3\n"
> \
> + "bne- 1b\n"
> \
> + : "=&r" (old), "+m" (*p)
> \
> + : "r" (mask), "r" (p)
> \
> + : "cc", "memory");
> \
> +}
> +
> +DEFINE_CLROP(clear_bits, "")
> +
> +static inline void set_bit(int nr, volatile void *addr)
> +{
> + set_bits(BITOP_MASK(nr), (volatile unsigned int *)addr + BITOP_WORD(nr));
> +}
> +static inline void clear_bit(int nr, volatile void *addr)
> +{
> + clear_bits(BITOP_MASK(nr), (volatile unsigned int *)addr +
> BITOP_WORD(nr));
> +}
> +
> +/**
> + * test_bit - Determine whether a bit is set
> + * @nr: bit number to test
> + * @addr: Address to start counting from
> + */
> +static inline int test_bit(int nr, const volatile void *addr)
> +{
> + const volatile unsigned long *p = (const volatile unsigned long
> *)addr;
> + return 1UL & (p[BITOP_WORD(nr)] >> (nr & (BITOP_BITS_PER_WORD-1)));
Nit: Too deep indentation. Plus blanks around - please. I also don't see
the need for the UL suffix, when the function returns int only (and really
means to return bool, I assume, but int is in line with x86 and Arm, I
expect).
> +}
> +
> +static inline unsigned long test_and_clear_bits(unsigned long mask, volatile
> void *_p)
> +{
> + unsigned long old, t;
> + unsigned int *p = (unsigned int *)_p;
> +
> + asm volatile (
> + PPC_ATOMIC_ENTRY_BARRIER
> + "1: lwarx %0,0,%3,0\n"
> + "andc %1,%0,%2\n"
> + "stwcx. %1,0,%3\n"
> + "bne- 1b\n"
> + PPC_ATOMIC_EXIT_BARRIER
> + : "=&r" (old), "=&r" (t)
> + : "r" (mask), "r" (p)
> + : "cc", "memory");
> +
> + return (old & mask);
> +}
> +
> +static inline int test_and_clear_bit(unsigned int nr,
> + volatile void *addr)
Nit: Too deep indentation again.
> +{
> + return test_and_clear_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr)) != 0;
> +}
> +
> +#define DEFINE_TESTOP(fn, op, eh)
> \
> +static inline unsigned long fn(
> \
> + unsigned long mask,
> \
> + volatile unsigned int *_p)
> \
And yet once more (and there are more below).
> +{
> \
> + unsigned long old, t;
> \
> + unsigned int *p = (unsigned int *)_p;
> \
> + __asm__ __volatile__ (
> \
> + PPC_ATOMIC_ENTRY_BARRIER
> \
> +"1:" "lwarx %0,0,%3,%4\n"
> \
> + #op "%I2 %1,%0,%2\n"
> \
> + "stwcx. %1,0,%3\n"
> \
> + "bne- 1b\n"
> \
> + PPC_ATOMIC_EXIT_BARRIER
> \
> + : "=&r" (old), "=&r" (t)
> \
> + : "rK" (mask), "r" (p), "n" (eh)
> \
> + : "cc", "memory");
> \
> + return (old & mask);
> \
> +}
> +
> +DEFINE_TESTOP(test_and_set_bits, or, 0)
> +
> +static inline int test_and_set_bit(unsigned long nr, volatile void *addr)
> +{
> + return test_and_set_bits(BITOP_MASK(nr), (volatile unsigned int *)addr +
> BITOP_WORD(nr)) != 0;
Too long line.
> +}
> +
> +/**
> + * __test_and_set_bit - Set a bit and return its old value
> + * @nr: Bit to set
> + * @addr: Address to count from
> + *
> + * This operation is non-atomic and can be reordered.
> + * If two examples of this operation race, one can appear to succeed
> + * but actually fail. You must protect multiple accesses with a lock.
> + */
> +static inline int __test_and_set_bit(int nr, volatile void *addr)
> +{
> + unsigned int mask = BITOP_MASK(nr);
> + volatile unsigned int *p =
> + ((volatile unsigned int *)addr) + BITOP_WORD(nr);
> + unsigned int old = *p;
> +
> + *p = old | mask;
> + return (old & mask) != 0;
> +}
> +
> +/**
> + * __test_and_clear_bit - Clear a bit and return its old value
> + * @nr: Bit to clear
> + * @addr: Address to count from
> + *
> + * This operation is non-atomic and can be reordered.
> + * If two examples of this operation race, one can appear to succeed
> + * but actually fail. You must protect multiple accesses with a lock.
> + */
> +static inline int __test_and_clear_bit(int nr, volatile void *addr)
> +{
> + unsigned int mask = BITOP_MASK(nr);
> + volatile unsigned int *p =
> + ((volatile unsigned int *)addr) + BITOP_WORD(nr);
> + unsigned int old = *p;
> +
> + *p = old & ~mask;
> + return (old & mask) != 0;
> +}
> +
> +#define flsl(x) generic_flsl(x)
> +#define fls(x) generic_fls(x)
> +#define ffs(x) ({ unsigned int __t = (x); fls(__t & -__t); })
> +#define ffsl(x) ({ unsigned long __t = (x); flsl(__t & -__t); })
Hmm, here you even have two underscores as prefixes.
> +/* Based on linux/include/asm-generic/bitops/ffz.h */
> +/*
> + * ffz - find first zero in word.
> + * @word: The word to search
> + *
> + * Undefined if no zero exists, so code should check against ~0UL first.
> + */
> +#define ffz(x) __ffs(~(x))
> +
> +/**
> + * hweightN - returns the hamming weight of a N-bit word
> + * @x: the word to weigh
> + *
> + * The Hamming Weight of a number is the total number of bits set in it.
> + */
> +#define hweight64(x) generic_hweight64(x)
> +#define hweight32(x) generic_hweight32(x)
> +#define hweight16(x) generic_hweight16(x)
> +#define hweight8(x) generic_hweight8(x)
Not using popcnt{b,w,d}, e.g. via a compiler builtin?
> +/* Based on linux/include/asm-generic/bitops/builtin-__ffs.h */
> +/**
> + * __ffs - find first bit in word.
> + * @word: The word to search
> + *
> + * Undefined if no bit exists, so code should check against 0 first.
> + */
> +static /*__*/always_inline unsigned long __ffs(unsigned long word)
What's this odd comment about here?
> +{
> + return __builtin_ctzl(word);
> +}
> +
> +/**
> + * find_first_set_bit - find the first set bit in @word
> + * @word: the word to search
> + *
> + * Returns the bit-number of the first set bit (first bit being 0).
> + * The input must *not* be zero.
> + */
> +#define find_first_set_bit(x) ({ ffsl(x) - 1; })
Simply
#define find_first_set_bit(x) (ffsl(x) - 1)
without use of any extensions?
> +/*
> + * Find the first set bit in a memory region.
> + */
> +static inline unsigned long find_first_bit(const unsigned long *addr,
> + unsigned long size)
> +{
> + const unsigned long *p = addr;
> + unsigned long result = 0;
> + unsigned long tmp;
> +
> + while (size & ~(BITS_PER_LONG-1)) {
> + if ((tmp = *(p++)))
> + goto found;
> + result += BITS_PER_LONG;
> + size -= BITS_PER_LONG;
> + }
> + if (!size)
> + return result;
Just using 4-blank indentation isn't enough to make this Xen style.
(More such elsewhere.)
> + tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
> + if (tmp == 0UL) /* Are any bits set? */
> + return result + size; /* Nope. */
> +found:
Labels indented by at least one blank please. (More elsewhere.)
Jan
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |